Challenges Posed by Climate Change and Sedimentation of Reservoirs for Flood Mitigation and Sustained Water Supply

The global climate crisis increases variability in the water cycle, reduces the predictability of water availability, affects water quality and aggravates water scarcity. These are compounded by number of contributing factors, including population increase, unmanaged migration, land use changes, reduced soil health, accelerated groundwater extraction, widespread ecological degradation and biodiversity loss. While all regions of the globe are affected, the impacts of climate change are highly variable. Some regions are experiencing drought while others are facing frequent-intensified floods and storms. in the past three years Bhakra Beas Management Board (BBMB) has tackled the problems posed due to climate change including drought, floods, historical minimum and maximum snow deposition, one of the highest inflows and witnessed maximum rainfall in sub-catchments in the century. It is often said that climate change impacts are observed more straight forward through water resources. Transboundary cooperation as well as cooperation between different states/provinces is needed to address climate impacts that cross national boundaries, to minimize adverse consequences from a basin perspective and also to harness the potential co-benefits of improved regional cooperation, such as reduced uncertainty due to exchange of data, enlarged planning space and shared costs and benefits.

Bhakra Beas Management Board operates two major reservoirs formed by Bhakra and Pong Dam, comprising varying inflows from 19–35 billion cubic meter (BCM) in a water year with average inflow of 27 BCM for both the reservoirs. The designed capacity of Bhakra and Pong Dam is 9.87 BCM and 8.58 BCM respectively from which the average water of 27 BCM from both reservoirs is supplied to the partner states. These reservoirs provide food and energy security and great immunity in case of droughts and floods in the North-West India. Due to sedimentation storage capacity of Bhakra and Pong reservoir reduced by 23% and12% respectively. Area downstream of the dams face danger especially in case of floods. The rivers beds are silted up and rivulets having catchment area downstream of the dams are carrying high inflows flood large areas.

To encapsulate the climate change, Bhakra Beas Management Board has taken various initiatives such as climate change studies, soil erosion hot spot identification, sediment transfer, both agriculture and non-agriculture productive use of sediments in the reservoir. The climatic studies show that by 2070 precipitation in Satluj and Beas basins would increase by 94 mm and 79 mm respectively compared to long term average of the year 1960–90 and temperature in these basins is likely to increase by 2.22 and 2.24 degree Celsius respectively. Systematic database and analysis of snow position, seasonal forecasting along with modern mathematical models is being done to minimize water scarcity conditions as well as to tackle the extreme floods. The paper brings out case study of the Beas and Satluj river basins.